1. Field of the Invention
The present invention relates to a planar electric precipitator, particularly to a planar electric precipitator which is easy to manufacture and of flat shape to be suitable for industrial and home use.
2. Description of Related Art
In conventional art, particles suspended in the air are removed by letting an air flow pass through a channel in which a pointed electrode is placed. Direct voltage between the electrode and a collecting plate causes the particles contained in the air flow to be ionized and drawn towards the collecting plate and thus to be removed from the air.
Electrostatic air cleaning apparatuses as just described work effectively and therefore are widely used to clean air in closed rooms. However, conventional electrostatic air cleaning apparatuses generally have large volumes and need to be placed on floors, which consumes valuable space and is inconvenient.
The main reason for a large volume of a conventional electrostatic air cleaning apparatus lies in a large thickness due to required distances between electrodes and collecting plates and the need to install several layers of electrodes and collecting plates for better effectivity.
Another shortcoming of conventional electrostatic air cleaning apparatuses is the difficulty during manufacture of precisely controlling distances and mutual orientations between electrodes and collecting plates, so as to prevent smoke from entering air channels and preserving ionizing capability.
The present inventor has been aware that conventional art does not solve the problems of large volume, difficulty of manufacturing and cost reduction. U.S. patent publication no. US005925170A “Electric dust-collection unit and air-cleaning apparatus” discloses an electrostatic air cleaning apparatus having a plurality of electrodes, each made of a wire with a needle tip, oriented parallel to each other, which results in a large thickness and hence a large volume of the apparatus. Furthermore, the electrodes, being separable from a base, during manufacture need to be placed precisely one by one, which is difficult and expensive.
U.S. patent publication no. US006524369B1 “Multi-stage particular matter collector” discloses an electrostatic air cleaning apparatus having a plurality of electrodes, each being a metal plate with sharp edges, vertically placed on a horizontal collector plate. Therefore, the apparatus has a height that is hard to reduce, resulting in a large volume.
U.S. patent publication No. US005322550A “Electrical dust collector” discloses an electrostatic air cleaning apparatus having a plurality of electrodes which are made by punching and bending a metal plate and a plurality of collecting plates made by punching and bending a metal plate, too, and interleaving with the plurality of electrodes. This apparatus has a somewhat reduced thickness, but a satisfactorily small volume is not achieved. Furthermore, manufacturing by punching and bending into precise angles is difficult due to the elasticity of metal plates, so that precision and hence effectivity of the apparatus are not sufficiently high.
U.S. patent publication No. US005492557A “Filter device for air purification” discloses an electrostatic air cleaning apparatus having a plurality of electrodes which are made from a metal plate by punching a plurality of holes with pointed flaps reaching inside and being bent away at predetermined angles to form electrodes. Thereby the apparatus is almost flat, but a minimum thickness is still required by orienting a collecting plate perpendicular to the electrodes.